The Applicant has developed a range of Memjet® inkjet printers as described in, for example, WO2011/143700, WO2011/143699 and WO2009/089567, the contents of which are herein incorporated by reference. Memjet® printers employ a stationary printhead in combination with a feed mechanism which feeds print media past the printhead in a single pass. Memjet® printers therefore provide much higher printing speeds than conventional scanning inkjet printers.
Multi-color Memjet® printhead cartridges are generally based on the liquid crystal polymer (LCP) manifold described in U.S. Pat. No. 7,347,534, the contents of which are incorporated herein by reference. A plurality of butted Memjet chips are bonded to a surface of the LCP manifold via an apertured die-attach film. The LCP manifold cooperates with the die-attach film to direct ink from each of five main ink channels to respective color planes of each Memjet® chip via a series of tortuous ink paths.
As described in U.S. Pat. No. 8,025,383, the contents of which are incorporated herein by reference, the LCP manifold additionally incorporates a series of air boxes positioned above the five main ink channels for dampening hydrostatic pressure fluctuations.
Memjet® printhead cartridges, comprising the LCP manifold described above, provide a versatile platform for the construction of a wide range of single-pass inkjet printers, including office, label, wideformat and industrial printers. Industrial printers typically have a plurality of printheads aligned in a media feed direction, as described in U.S. Pat. No. 8,845,080, the contents of which are incorporated herein by reference.
Although the Memjet® printhead cartridge is designed for multi-color printing, some types of printer require monochrome printing only. For example, the industrial printers described in U.S. Pat. No. 8,845,080 employ five monochrome printhead cartridges in order to maximize print speeds. Trivially, the LCP manifold can be plumbed with one color of ink to provide monochrome printing from the nominally five-color Memjet® printhead chips. However, at very high print speeds, the LCP manifold has some practical limitations. The multiple labyrinthine ink pathways from the LCP manifold to the printhead chips may be responsible for unexpected de-priming when the printhead is running at high speeds. Without a sufficient body of ink close to the printhead chips, the chips may become starved of ink under periods of high ink demand and lead to chip de-priming. Secondly, the labyrinthine ink pathways are susceptible to trapping air bubbles; if an air bubble become trapped in the system, the printhead chips will become starved of ink and de-prime. Thirdly, the air boxes provide a relatively stiff compliance in the hydrostatic system; if a particular group of nozzles demands higher ink flow, then the resistance of the air boxes may be too great to allow the hydrostatic system to respond dynamically to the increased demand.
It would therefore be desirable to provide a printhead assembly configured for high-speed monochrome printing, which addresses at least some of the shortcomings of the LCP manifold described above.